Device for actuation of reed switches



y5. 7 I P. BOZZOYNE 3,510,813

DEVICE FOR ACTUAIION OF REED SWITCHES Filed April 18, 1968 United States Patent 6,074 Int. Cl. H0111 1/66 U.S. Cl. 335-405 3 Claims ABSTRACT OF THE DISCLOSURE A reed switch actuating device comprising a frame of magnetic material interconnecting the pole pieces of a bar magnet is described. The frame completes the magnetic circuit whereby the magnet cannot act on the reed switch. The frame may be opened, breaking the magnetic circuit for actuation of the reed switch.

Contacts formed by elastic elements of ferromagnetic material positioned in a glass envelope and hermetically sealed find various applications and are generally known as reed switches. The closure of the contacts is effected by movement of the elastic elements against each other when they are subjected to the influence of a properly polarized magnetic field.

Various means are known for closing such contacts. One of these comprises an electric coil inside of which contacts are placed so that the magnetic field produced by this coil will close the contacts. Another type of actuation utilizes a permanent magnet placed near the contacts.

The first type requires the use of a source of electrical current for the coil. The second type of actuation requires displacement of the permanent magnet so as to safely control the opening and the closing of the contact.

The present invention proposes to remedy the drawbacks of the previously mentioned types of actuation. It has for its object a device for the actuation of the contacts of the reed switch by magnetic means, comprising a magnetic circuit consisting of at least one permanent magnet the pole pieces of which are interconnected by ferromagnetic members. One of the members is capable of occuping two positions, corresponding to the opening and closing of the magnetic circuit, in such a way that the opening of this circuit creates a field effecting the closing of the contacts.

The accompanying drawings represents by way of example two modifications of the present invention.

FIGS. 1 and 2 illustrate the first modification in rest position and in active position respectively.

FIGS. 3 and 4 illustrate the second embodiment in which the devices actuates two reed switches.

The device shown in FIGS. 1 to 4 consists of a permanent magnet 1, in the shape of a bar, each pole of this magnet being connected to a polar member 2, 3, respectively, of ferromagnetic material. These members are formed of two L-shaped sections perpendicular to one another. As can be seen in FIGS. 1 and 3, the dimensions of each of these sections are calculated in such a way as to constitute a rectangular frame. Member 2 is stationary while member 3 is movable around a pivot 4. A return spring 5 secured to member 3 urges this member to pivot around the stud 4 in a counterclockwire direction in order to press the end of the member 3,510,813 Patented May 5, 1970 "ice 3 against that of the member 2 thus forming a closed magnetic circuit.

A reed switch 6 is positioned parallel to bar magnet 1 facing polar members 2 and 3. The switch 6 is formed of two elastic blades or reeds 7 and 8 positioned inside a glass envelope 9 which is hermetically sealed.

In the example shown in FIGS. 3 and 4, a second reed switch 10 identical with that of switch 6 is positioned parallel to bar magnet 1 and adjacent thereto.

As shown in FIGS. 2 and 4, a force F can be applied to polar piece section 3 in such a way as to make it pivot around pivot 4 in a clockwise direction thus creating an air-gap 11 between the free ends of polar members 2 and 3. The opening of the magnetic circuit permits the field of the magnet 1 to act on the switch 6, bringing together the reeds and consequently the closure of contacts 7 and 8, respectively. When force F ceases to be exerted on polar member 3, the latter is brought back against member 2 by the magnetic attraction on the one hand and by the force of spring 3, causing closure of the magnetic circuit. The air-gap between elements 2 and 3 being closed, the field of the magnet is insufficient for the actuation of the switch 6, therefore contacts 7 and 8 remain open.

In the example shown, the magnetic circuit of the device is normally closed. It is evident that its functioning can also be inverted. It suffices for this that the force of the return spring be exerted in the opposite direction and maintains the polar member in the rest position corresponding to that shown in FIGS. 2 and 4.

What is claimed is:

1. A reed switch actuating device consisting of a permanent bar magnet in substantially parallel relation to the contacts of said switch and of such strength as to cause the closure thereof, a frame of ferromagnetic material interconnecting the pole pieces of said magnet providing a closed magnetic circuit for the flux thereof whereby closure of said switch is prevented, said frame having a displaceable member whereby, upon displacement thereof, said magnetic circuit is opened allowing the flux of said permanent magnet to close said switch, and means for causing displacement of said member for the actuation of said switch.

2. A reed switch actuating device in accordance with claim 1, said frame comprising two L-shaped sections, pivot means for displacing one of said sections and spring means urging said sections into closure between pole pieces of said bar magnet.

3. A reed switch actuating device in accordance with claim 2 wherein one reed switch is placed adjacent said magnet and another reed switch adjacent said sides of said L-shaped section which are parallel to said magnet, whereby upon displacement of said section both of said switches are subjected to the field of said magnet for actuation.

References Cited UNITED STATES PATENTS 3,184,563 5/1965 Myatt 335l53 BERNARD A. GILHEANY, Primary Examiner R. N. ENVALL, JR., Assistant Examiner U.S. Cl. X.R. 335-206 

